Showing papers on "Allelopathy published in 1984"

Allelopathic Effects of Lantana (Lantana camara) on Milkweedvine (Morrenia odorata)1

Abstract: Allelopathic effects of lantana (Lantana camara L. #3 LANCA) residues (root, shoot), foliar leachates, and the soil (where lantana was grown) on milkweedvine (Mor- renia odorata Lindl. #3 MONOD) seed germination and growth over a 30-day period were examined. Foliar leachates or the soil collected from the field where lantana had been growing had no effect on the final germination percentage or the seedling growth of milkweedvine. Incorporation of dried lantana shoot or root material into soil had no ef- fect on the final percentage germination but caused signifi- cant reductions in milkweedvine growth over a 30-day test period. Roots were more inhibitory than shoots. Fifty percent of milkweedvine seedlings died within 15 days after germination at 1% (w/w) dried lantana root incorpora- tion into the soil, and higher concentrations increased seedling death. Lantana roots incorporated into the soil produced foliar symptoms such as wilting and desiccation, whereas lantana shoots incorporated into the soil produced yellowing of the foliage of milkweedvine. Allelopathic ac- tivity of lantana residues was still strong even after decomposi- tion of lantana residues for 4 weeks prior to the planting of milkweedvine seeds. Additional index words. Allelopathy, germination, LANCA,

Chemical defense of Leguminosae. Are quinolizidine alkaloids part of the antimicrobial defense system of lupins

Abstract: Growth of 6 bacteria (Serratia marcescens, Bacillus megaterium, Bacillus subtilis, Streptococcus viridis, Micrococcus luteus, and Mycobacterium phlei) was inhibited by 50% if the growth medium contained sparteine at concentrations between 0.5-10mᴍ. Total growth inhibition, which was bacteriostatic in nature, was achieved at 20 mᴍ. The growth of 6 phytopathogenic fungi was also affected: at a sparteine concentration of 15 mᴍ the growth of Alternaria porri was reduced by 40% as compared to the untreated control. Respective values were 18% inhibition for Piricularia oryzae, 33% for Helminthosporium carbonum, 15% for Rhizoctonia solani, 5% for Fusarium oxysporum, and 42% for Asperquillus oryzae. Since the concentrations of quinolizidine alkaloids range from 1-200 mᴍ (roots, leaves, or stems) or 10-200 mmol/kg (seeds) in Leguminosae, it is discussed whether quinolizidine alkaloids are involved in the antimicrobial defense of lupins, in addition to their potential role as allelopathic or herbivore repellent defense compounds.

Datura stramonium allelochemicals: longevity in soil, and ultrastructural effects on root tip cells of helianthus annuus l.

Abstract: Summary Allelopathic alkaloids from Datura stramonium seeds remained phytotoxic to Helianthus annuus for 15 weeks in soil under field conditions Studies using transmission electron microscopy showed that these alkaloids retarded the metabolism of food reserves, particularly starch, in germinating H annuus seeds Structural damage to cells and organelles was not apparent

Allelopathic effects of Eupatorium riparium on population regulation of two species of Galinsoga and soil microbes

Abstract: Allelopathic effect ofEupatorium riparium Regel, a dominant ruderal weed at higher altitudes in Meghalaya state in north-eastern India, was studied on two common sympatric annual weeds,Galinsoga ciliata (Raf.) andG. parviflora Cav. and on soil microbes. Seed germination and radicle and plumule growth of both species ofGalinsoga were suppressed by the aqueous extract and leachate ofE. riparium. Although the leaf leachate, leaf and litter extracts and litter bed caused considerable reduction in leaf area and seed and dry matter production in both species ofGalinsoga, the effect was much more pronounced onG. parviflora. The inhibitory effect was directly correlated with the concentration of the extract and leachate. The soil microbial population and growth of theGalinsoga spp. declined considerably in the experimental pots where the soil had earlier received leachate of different plant parts ofE. riparium growing in it. The presence of the partly decomposed litter ofE. riparium in the pots reduced soil microbial population and growth of the two weeds much more strongly as compared to the litter in the advanced stages of decomposition. The study also revealed that the abundance and colony growth of the two test fungiviz. Trichoderma viride andAspergillus flavus were differentially affected by the allelopathy ofE. riparium; T. viride being favoured andA. flavus inhibited.

Allelopathic Interactions of some Tropical Weeds

Abstract: Allelopathic influence of some tropical weeds was studied on the growth and development of wheat and mungbean, as also on nitrogenase activity and growth of Rhizobium culture. It was observed that a few weeds have promotory allelopathic effects and such effects are species specific. Chenopodium album had promotory effects on growth and development of wheat and mungbean and also on nitrogenase activity and Rhizobium culture. Celosia argentea, Rumex dentatus and Phalaris minor also promoted wheat growth and increased grain yield. R. dentatus increased mungbean growth and nitrogenase activity. Avena ludoviciana and Cirsium arvense though increased the growth, depressed the niirogenase activity. The promotion or inhibi-tion of Rhizobium growth depended on the concentration of the extracts in the medium.

Studies on allelopathy among higher plants. III. Allelopathic substances from Spergula arvensis L.

Abstract: 農耕地に繁茂する一年生雑草オオツメクサ (Spergula arvensis L.) の遺体および茎葉部の水抽出液の作物の発芽ならびに初期生育に対する影響を検討した。また, 同時にペーパー, 薄層および高速液体クロマトグラフィを利用してオオツメクサの生長抑制物質の同定を行った。1. オオツメクサの茎葉部の土壌混和処理によって, カブ, トマトおよびダイコンの出芽が抑制され, 初期生育も劣った。また, 茎葉部の水抽出液散布処理も土壌混和処理同様, カブ, トマト, ダイコンの出芽ならびに初期生育を抑制した。2. オオツメクサの茎葉部水抽出液はイネ幼苗の生長を抑制した。その程度は濃度によって異なり, 濃度が高いほど生長抑制は大きかった。3. オオツメクサ茎葉部の70%メタノール抽出物の酸性画分を検討した結果, イネの第2葉鞘の伸長を抑制する物質としてカフェー酸およびフェルラ酸が推定された。4. 標品のカフェー酸およびフェルラ酸は10ppmの濃度においてイネ幼苗の生長を抑制した。その程度は濃度が高いほど著しかった。

Effects of 1,1-Dimethylpiperidinium Chloride on the Pests and Allelochemicals of Cotton and Pecan.

Abstract: The growth regulator, PIX (mepiquat chloride l,l-dimethyl-piperdinium chloride), when applied to cotton (Gossypium hirsutum L.) and pecan (Carya illinoensis Koch), caused internode shortening. PIX did not elicit an increase in resistance in cotton to the tobacco budworm[Heliothis virescens (Fab.)], or in pecan to pecan scab (Cladosporium caryigenum (Ell. et Lang) Gottwald]. Also, changes in content of four known allelochemicals (condensed tannins, gossypol, anthocyanins, flavonoids) for these pests were minimal. An unexpected finding was the increase in content of several nutritional factors that may be related to greater, rather than lesser, growth of tobbaco budworm larvae feeding on cotton tissues.